The present invention relates to a method for orientating a liquid crystalline polymer and more particularly to a method for preparing highly orientated, liquid crystalline polymer having a light controlling function and suitable for use in the optoelectronic field.
Generally, for using a liquid crystal as a device it is necessary to orientate the molecules of the liquid crystal in a certain arrangement, but this molecular orientation is changed by external force such as electric and magnetic fields, shear force, and interface. And a light controlling function derived from such change of the orientation is utilized for the application to various optoelectronics.
Liquid crystals are broadly classified into high-molecular liquid crystals and low-molecular ones. The former (high-molecular liquid crystals) are greatly characteristic in that they are used in a fixed state of their functions by fixing the orientated state of their molecules. Thus, the former liquid crystals are applied to fields different from the fields in which the latter-low-molecular liquid crystals are used. For example, such high-molecular liquid crystals are applied to an orientated film for low-molecular liquid crystals (described in Japanese Patent Laid Open No. 42618/1986), a non-linear optical element (described in Japanese Patent Laid Open No. 201419/1987), a circular polarization filter and a notch filter (both described in Japanese Patent Laid Open No. 191203/1985), and an optical memory (described in Japanese Patent Laid Open No. 66990/1987). In order to realize these applications it is necessary to highly control to a desired molecular orientation.
A method for controlling the state of orientation of a low-molecular liquid crystal using an orientated film has already been established and now serves as a basic technique for a twisted nematic or super twisted nematic type liquid crystal display. As to the method for controlling the state of orientation of high-molecular liquid crystals, there has been known a method (e.g. a method of providing an external force such as shear stress or a method of providing such an external force as electric or magnetic field) in which, in a certain limited region, the molecules of a high-molecular liquid crystal are orientated with an order Parameter higher than that in low-molecular liquid crystals irrespective of whether the liquid crystal is a nematic smectic or cholesteric type. But these methods involve inconveniences; for example, it is impossible to control the orientation over a wide area, or an intra-plane uniaxial orientation cannot be controlled even though a horizontal orientation can be effected. Thus, it is now impossible to say that there is an established technique for highly controlling the orientation of a high-molecular liquid crystal and fixing it.